Unanswered Question
Jan 27th, 2015
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I wonder if there are any clues that helps to extract as much information about users behind proxy as possible? We're migrating ASA 5520 to new ASA with firepower module, but there's a proxy on inside network, talking to ASA with WCCP. So source IP will be always single PROXY address, and domain username is also lost. 

The only possibility I can see is extracting original client ip from X-Forwarded-For header. It can be a solution, but: On intrusion event tab I can add "Original Client IP" column ( this feature is not working by the way on my (build 37) - field is always empty, even if I can see X-Forwarded-For in packet details ). Additionaly, on AMP submenu I can't see any place where "Original Client IP" could be viewed? 

Placing Proxy behind any other interface than inside would be a nicer solution, but WCCP on ASA doesn't support it. 


Would be grateful for any help



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zaferberber Wed, 02/03/2016 - 11:05
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Internet<--> IPS <-->Proxy <-->Client

if the proxy send client ip address with "X-Forwarded-Fo"r how can i read this information with sourcefire and when packet leaves from Sourcefire i want remove "X-Forwarded-For".

is that possible?


ankojha Wed, 05/04/2016 - 10:24
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Yes, we can disable this XFF information under Policy->Acces control->Network Analysis policy ->tcp preprocessor.

Rate if that helps.



miculp Wed, 05/04/2016 - 17:13
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Sourcefire (aka Firepower), at this time, does not have a way to strip the XFF header off the packet.

miculp Sat, 02/27/2016 - 23:14
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I would recommend that you verify that "extract XFF" is enabled in the HTTP preprocessor.

~ Cheers

Igor Mordiuk Wed, 03/02/2016 - 05:45
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In the HTTP preprocessor turned on "Extract Original Client IP Address", but still see only Proxy's ip address in Analysis->Connections ->Events.

How to obtain original ip, not proxy's ???

Hrvoje Samec Wed, 04/27/2016 - 01:56
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Did you manage to solve this?
I have the same problem, "Extract Original Client IP Address" is enabled, but in event logs I still see only proxy IP as Initiator IP

miculp Wed, 05/04/2016 - 17:11
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The default headers that can be extracted from a packet are X-Forwarded-For and True-Client-IP. If you have a proxy using "Original Client IP Address" (confirm in the packet) then you can add this to the HTTP preprocessor.

Bill CARTER Wed, 07/27/2016 - 11:23
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I had this issue also. There are a couple of settings in the HTTP preprocessor.

Firepower 6.0

Go to Policies -> Access Control -> Network Analysis Policy (Top right of browers window).

Edit existing policy, or create new policy.

Policy information -> Settings -> HTTP Configuration

Under Targets click + to add a server and enter the IP address, CIDR, or comma-seperated list. Click OK.

Then check boxes "Detect HTTP Proxy Servers", "Allow HTTP Proxy use", and "Extract Original Client IP Address".

For mine I have "XFF Header Priority" with #1 "X-Forward-For"

Hope this helps.


Carlos Alberto ... Wed, 10/26/2016 - 10:56
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Hello Guys,

How can i enable "extract XFF" on FMC 6.1? I cannot find Network Analysis Policy section.

miculp Tue, 12/06/2016 - 14:36
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It's been moved from the intrusion policy (<= 5.4.x) to the advanced tab in the access control policy. 


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